To determine which of the given options is a monomial, we need to recall the definition of a monomial. A monomial is an algebraic expression that consists of only one term.
Now let's analyze each option:
A. [tex]\( 3x^2 + 2x - 1 \)[/tex]
- This expression has three terms: [tex]\( 3x^2 \)[/tex], [tex]\( 2x \)[/tex], and [tex]\( -1 \)[/tex].
- Since a monomial must have only one term, this is not a monomial.
B. [tex]\( 2x - 1 \)[/tex]
- This expression has two terms: [tex]\( 2x \)[/tex] and [tex]\( -1 \)[/tex].
- Since a monomial must have only one term, this is not a monomial.
C. [tex]\( 3x + 4 \)[/tex]
- This expression has two terms: [tex]\( 3x \)[/tex] and [tex]\( 4 \)[/tex].
- Since a monomial must have only one term, this is not a monomial.
D. [tex]\( 4 \)[/tex]
- This expression has only one term: [tex]\( 4 \)[/tex].
- Since a monomial can be a constant (a single term with no variables), this is a monomial.
Therefore, the best answer to the question "Which of the following is a monomial?" is:
D. [tex]\( 4 \)[/tex]
